Each time two conduits are secured to each other the resulting connection must be sealed to prevent the escape of pressurized fluid flowing in the conduits. It is well known that increasingly high pressures place correspondingly more stringent requirements on the seal between the conduits. The most common manner of sealing two conduit ends while permitting their separation is with well-known flange connections. Briefly, such connections comprise a pair of flat, radial flanges which define opposing end faces that are drawn together with a multiplicity of circumferentially spaced, threaded bolts. A seal ring, normally a simple O-ring, is placed in a suitably designed groove between the opposing end faces and prevents the escape of pressurized fluid from between the two flanges.
Such connections have the advantage that they are suitable for even the highest pressure applications. Moreover, manufacturing tolerances are relatively loose since the opposing flanges can be tightened as much as necessary to generate the desired, axially acting sealing force between the seal ring and the opposing flange faces. However, the seal can tolerate virtually no deflection between the flanges. As a consequence the flanges must be relatively massive and a large number of bolts is required to maintain the flanges in a rigid, non-yielding face-to-face contact when pressure is applied to the conduit.
For applications in which there is only limited access such a conduit connection is not feasible. For example, in high radiation areas such as are found in nuclear reactors and the like access to the flanged connection is often only possible via remote-controlled equipment. Such equipment is inherently ill-equipped to form conduit connections by placing and tightening large numbers of circumferentially spaced bolts. To overcome this problem it is necessary to either provide very expensive and fail-prone handling equipment capable of applying and releasing the above-described flange connection or, in the alternative, to form seal-tight conduit connections which do not rely on the relatively high contact pressure required of face seals. Such connections, however, require very close tolerances and high-quality surface finishes which are easily damaged during handling. Accordingly, both alternatives are expensive and the latter is fail-prone. As always, high cost is undesirable. In installations involving radioactive materials failure of a connection is intolerable.
The problem is compounded when a seal-tight, releasable connection is to be formed between pairs of inner and outer conduits wherein both conduits must be simultaneously sealed. Such an application can again be found in areas of high radioactivity such as in a so-called Tokamak Fusion Test Reactor, a device contemplated for burning long-lived actinide waste produced in fission reactors to transform long-lived fission reactor waste products into more acceptable, shorter-lived radioactive waste products before their ultimate disposal. In such fusion reactors it is contemplated to place the actinide pellets in several containers each of which is enclosed within a housing and to flow a suitable cooling medium from each housing into the corresponding container. The housings-container sets are in turn releasably mounted to a double, i.e., an inner and an outer manifold for circulation of the cooling medium. The containers must be periodically replaced and since they are in a radioactively contaminated area access to the containers is possible only via remote handling equipment. For the above-described reasons conventional flanged connections are not feasible. Similarly, other types of sealed, releasable conduit connections such as those relying upon close tolerances and high-quality surface finishes to establish a seal are not sufficiently fail-safe for installations of this type.